JP6598604B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  An electrophotographic image forming apparatus employs a heat fixing method in which a toner image is heated and fixed by a heater. From the viewpoint of power saving, a relay is provided in each of the hot line and the neutral line for supplying power to the heater. Since relay contacts are welded due to aging, the presence or absence of welding must be detected from the viewpoint of protecting the heater. In Patent Document 1, relay welding detection is performed both at the start and end of image formation.

JP 2012-042573 A

  However, an image forming apparatus that performs welding detection at the start of image formation cannot turn on the heater until the welding detection is completed. Since the image forming apparatus cannot execute image formation until the heater temperature reaches the target temperature, the waiting time of the user increases due to the detection of welding. SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of reducing the waiting time associated with detection of welding of a relay as compared with the related art.

The present invention is, for example,
An image forming apparatus,
A first line that is one of a neutral line and a hot line that supplies power supplied from an AC power source to the load;
A second line which is the other of the neutral line and the hot line;
A first relay for turning on / off the first line;
A second relay for turning on / off the second line;
Monitoring means for monitoring a power supply state at a position subsequent to the first relay in the first line;
Relay control means for controlling on / off of each of the first relay and the second relay;
When the first execution condition is satisfied, first welding detection is performed to detect whether or not the first relay is welded according to the power supply state monitored by the monitoring unit, and the second execution condition is satisfied. And welding detection means for performing second welding detection for detecting whether or not the first relay is welded according to the power supply state monitored by the monitoring means;
Storage means for storing the result of the second welding detection,
The first execution condition is that the image forming apparatus is instructed to execute an image forming job, and the result of the second welding detection stored in the storage means is that the first relay is welded. Is that
The second execution condition is that the image forming apparatus ends the image forming job,
The welding detection means performs the first welding detection if the result of the second welding detection indicates that the first relay is welded, and indicates that the first relay is welded. If the second welding detection result does not indicate, skip the first welding detection,
The relay control unit controls the second relay to be on and the first relay to be off while the welding detection unit is executing the first welding detection or the second welding detection. And
Further, the relay control means provides an image forming apparatus that controls the first relay and the second relay to be turned on when an image forming job is started.

  According to the present invention, there is provided an image forming apparatus capable of shortening the waiting time associated with detection of relay welding as compared with the prior art.

Sectional view showing the image forming apparatus Block diagram showing the control system The figure which shows an electric power feeding circuit, a basic control part, and a fixing device Flow chart showing image forming process Flow chart showing second welding detection Flow chart showing first welding detection The figure which shows the function which CPU realizes

[Configuration of Image Forming Apparatus]
A schematic configuration of the image forming apparatus 100 will be described with reference to FIG. The image forming apparatus 100 may be an image forming apparatus that forms a single-color image, but here it is assumed to be an image forming apparatus that forms a multicolor image. The image forming apparatus 100 may be any of a printing apparatus, a printer, a copier, a multifunction machine, and a facsimile. The image forming apparatus 100 has four stations that form toner images using yellow, magenta, cyan, and black developers (toners). In FIG. 1, reference numerals are given only to the components of the yellow station, but the same configuration can be adopted for all four stations. Each station functions as an image forming unit that forms a toner image using toner on an image carrier such as the photosensitive drum 111 or the intermediate transfer belt 116.

  The photosensitive drum 111 is a cylindrical image carrier or photoconductor that carries an electrostatic latent image or a toner image. The charging device 112 uniformly charges the photosensitive drum 111 rotating in the direction of arrow A. The exposure device 113 outputs laser light modulated based on the image information, and scans the surface of the photosensitive drum 111 with the laser light. Thereby, an electrostatic latent image is formed. The developing device 114 develops the electrostatic latent image using toner to form a toner image. The primary transfer roller 117 primarily transfers the toner image on the photosensitive drum 111 to the intermediate transfer belt 116. Intermediate transfer belt 116 rotates in the direction indicated by arrow B. The sheet P is fed to the sheet conveyance path by the sheet feeding roller 120. The sheet P may be called recording paper, recording material, recording medium, paper, transfer material, transfer paper, or the like. The sheet P is skew-corrected by the registration roller 121 and is conveyed to the secondary transfer portion formed by the intermediate transfer belt 116 and the secondary transfer roller 119. In the secondary transfer portion, the toner image conveyed by the intermediate transfer belt 116 is secondarily transferred to the sheet P. Thus, the primary transfer roller 117 and the secondary transfer roller 119 function as a transfer unit that transfers the toner image to the sheet. When the toner image and the sheet P pass through the nip formed by the fixing film 142 and the pressure roller 141, the fixing device 140 applies heat and pressure to the toner image and fixes the toner image on the sheet P. The fixing film 142 is provided with a heater. Thereafter, the sheet P is discharged to the discharge tray by the discharge roller 122. A maintenance door 145 that is opened when the fixing device 140 and the like are maintained is provided on the side surface of the image forming apparatus 100.

[Control system]
FIG. 2 is a block diagram illustrating a control system of the image forming apparatus 100. Reference numeral 110 denotes a basic control unit of the image forming apparatus 100. The CPU 171 controls the image forming unit 200 and the like according to a control program stored in the ROM 174. The RAM 175 stores information indicating the operation state of the image forming apparatus 100. A battery 176 is connected to the RAM 175. Therefore, the RAM 175 can hold the stored content even when power is not supplied from the commercial power supply to the image forming apparatus 100. Various loads such as a motor and a clutch for driving the image forming unit 200 are connected to the I / O port 173. Further, a temperature detection circuit 700 that detects the temperature of the fixing device 140 and a door sensor 750 that detects opening and closing of the maintenance door 145 are connected to the I / O port 173. When the state of the maintenance door 145 detected by the door sensor 750 is switched from opening (opening) to closing, the CPU 171 turns on the power supply 24VIL that generates a voltage of 24V. On the other hand, when the state of the maintenance door 145 detected by the door sensor 750 is switched from the door closing commission to the door opening, the CPU 171 turns off the power supply 24VIL that generates a voltage of 24V. This on / off may be realized by controlling the door switch 760. The door sensor 750 may be omitted. In this case, the door switch 760 is a mechanical switch that is turned off / on mechanically in conjunction with the opening / closing of the maintenance door 145.

  A power feeding circuit 500 is connected to the heater 601 disposed in the fixing device 140. The power feeding circuit 500 supplies an AC voltage from the AC power source 550 to the heater 601. A detection signal from a temperature sensor 602 disposed in the fixing device 140 is input to the temperature detection circuit 700. In the temperature detection circuit 700, the voltage level of the detection signal is correlated with the temperature of the heater 601. That is, the voltage level indicates the temperature of the heater 601. When the temperature of the heater 601 exceeds a predetermined temperature, the temperature detection circuit 700 outputs a control signal instructing power supply stop to the power supply circuit 500. The power feeding circuit 500 stops the supply of AC voltage from the AC power source 550 to the heater 601 in accordance with the control signal. Thus, when the temperature of the heater 601 exceeds a predetermined temperature, the supply of AC voltage is stopped to protect the heater 601.

  An operation unit 172 is connected to the CPU 171, and a notification message is displayed on the display device of the operation unit 172 or information input by the operator through the input device is received. The CPU 171 is also connected to an external I / F 400 that receives image data from an external device such as a PC (personal computer) and an image memory 300 that holds the image data. The CPU 171 sequentially outputs line data generated by expanding the image data to the exposure device 113 of the image forming unit 200.

[Power supply circuit]
FIG. 3 is a diagram illustrating a schematic configuration of the power feeding circuit 500. In the fixing device 140, a temperature sensor 602 such as a thermistor for detecting the temperature of the heater 601 is disposed. For example, the thermistor is an element whose resistance increases or decreases as the temperature increases. That is, the resistance value and the temperature are correlated. The temperature detection signal 604 output from the temperature sensor 602 is input to the control unit 110 and the temperature detection circuit 700. The controller 110 turns the semiconductor switch 510 on / off so that the voltage level of the temperature detection signal 604 matches the voltage level corresponding to the target temperature. That is, by controlling the electric power supplied to the heater 601, the fixing temperature of the fixing device 140 is adjusted to the target temperature. A control signal 512 for turning on / off the semiconductor switch 510 is output from the CPU 171. The semiconductor switch 510 is, for example, a triac. The temperature detection circuit 700 is a circuit that protects the heater 601 from an excessive temperature rise of the heater 601. When the temperature detection circuit 700 exceeds a predetermined temperature higher than the target temperature of the fixing device 140, the temperature detection circuit 700 outputs a supply stop signal 701 to stop the power supply to the heater 601. That is, the temperature detection circuit 700 opens the relay contact when the voltage level of the temperature detection signal 604 exceeds a voltage level corresponding to a predetermined temperature.

  A hot line H and a neutral line N for supplying an AC voltage are connected from an AC power source 550 that is a commercial power source to a heater 601 that is a load. A first relay 501 is disposed between the AC power source 550 and the heater 601 in the hot line H. In the neutral N, a second relay 502 is disposed between the AC power supply 550 and the heater 601. Note that the names of the first relay and the second relay are merely for convenience, and these names may be reversed. The first relay 501 is on / off controlled by a control signal 503 output from the I / O port 173. The second relay 502 is on / off controlled by a control signal 504 output from the I / O port 173. The zero cross detection circuit 505 detects the zero cross of the AC voltage supplied from the AC power supply 550 in the subsequent stage of the first relay 501 and outputs a detection signal 506 corresponding to the zero cross timing. The CPU 171 specifies the presence / absence and phase of the AC voltage based on the detection signal 506. That is, the CPU 171 determines whether or not the first relay 501 and the second relay 502 are welded based on the presence or absence of an AC voltage. Further, the CPU 171 executes wave number control for adjusting the amount of power supplied to the heater 601 with reference to the phase (zero cross point) of the AC voltage. The CPU 171 receives the detection signal 506 through the I / O port 173.

  The first AND circuit 702 outputs a control signal 704 indicating a logical product of the control signal 503 output from the CPU 171 through the I / O port 173 and the supply stop signal 701 output from the temperature detection circuit 700. If the control signal 704 is at a high level, the first relay 501 is turned on, and if the control signal 704 is at a low level, the first relay 501 is turned off. Note that the first relay 501 is also turned off when the drive voltage is not supplied from the 24VIL power source. The second AND circuit 703 outputs a control signal 705 indicating a logical product of the control signal 504 output from the control unit 110 and the supply stop signal 701 output from the temperature detection circuit 700. If the control signal 705 is high level, the second relay 502 is turned on, and if the control signal 705 is low level, the second relay 502 is turned off. Note that the second relay 502 is also turned off when the drive voltage is not supplied from the 24VIL power source. The control signals 503 and 504 and the supply stop signal 701 all indicate supply (relay on) at a high level and stop (relay off) at a low level. That is, when either one of the CPU 171 or the temperature detection circuit 700 instructs to turn off the relay, the relay is turned off. If the temperature detection circuit 700 is not instructing to turn off the relay, the CPU 171 can control one of the first relay 501 and the second relay 502 to be on and the other to be off. Such control is used in welding detection (welding test).

  As described above, the first relay 501 and the second relay 502 are connected to a 24VIL power source that is turned off / on in conjunction with the opening / closing of the maintenance door 145. That is, when the maintenance door 145 is open, the supply of the drive voltage from the 24VIL power supply is stopped, so the first relay 501 and the second relay 502 are turned off.

  In this embodiment, two mechanisms for protecting the heater 601 are provided. When the temperature detected by the temperature sensor 602 exceeds the threshold value Tmax1, the CPU 171 switches all of the semiconductor switch 510, the first relay 501 and the second relay 502 off. As a result, when the temperature of the heater 601 is excessive, power supply to the heater 601 is stopped. On the other hand, the temperature detection circuit 700 outputs a supply stop signal 701 when the temperature detected by the temperature sensor 602 exceeds a threshold value Tmax2 larger than the threshold value Tmax1. Thus, even when the CPU 171 cannot instruct to stop supplying power to the heater 601, the temperature detection circuit 700 can instruct to stop supplying power to the heater 601. Thus, the protection mechanism of the heater 601 may be doubled.

[flowchart]
The relay welding detection of the present embodiment will be described with reference to FIG. In S401, the CPU 171 determines whether any of the execution conditions for the first welding detection is satisfied. One execution condition is that, for example, power is supplied to the image forming apparatus 100 from a commercial power source and the CPU 171 is activated. One execution condition is that an instruction to execute an image forming job is given through the operation unit 172 or the host computer. Further, one of the execution conditions is that the image forming apparatus 100 has returned from sleep (power saving mode). Even if these conditions regarding the execution timing are satisfied, if the preconditions are not satisfied, the first welding detection is skipped. The precondition is that the welding of the first relay 501 has already been detected by the second welding detection. Therefore, in S401, the CPU 171 determines whether or not the welding of the first relay 501 has already been detected by the second welding detection. For example, the CPU 171 reads out the welding detection result held in the RAM 175 and determines whether or not the first relay 501 has been detected. If the welding has not been detected yet, the CPU 171 skips the first welding detection and proceeds to S402. If the welding has not been detected yet, the CPU 171 proceeds to S402. In S402, the CPU 171 executes the first welding detection. If welding of the first relay 501 is not detected by the first welding detection, the process proceeds to S404. When the welding of the first relay 501 is detected by the first welding detection, the CPU 171 stops or prohibits the execution of the image forming job.

  If it is determined in S401 that the relay is not welded by the second welding detection, the CPU 171 proceeds to S403. In S403, the CPU 171 switches on the first relay 501 and the second relay 502 to start supplying power to the heater 601. As a result, the AC voltage supplied from the AC power source 550 is applied to the heater 601. In S404, the CPU 171 starts the temperature control of the heater 601 described above. In step S405, the CPU 171 executes an image forming job. When the image forming job ends, the CPU 171 proceeds to S406. In S406, the CPU 171 executes second welding detection. The contents of the first welding detection and the contents of the second welding detection are the same. However, the first welding detection and the second welding detection differ not only in the execution timing but also in that the first welding detection can be omitted according to the result of the second welding detection.

  The power state after completion of image formation depends on the setting state of the image forming apparatus 100. The CPU 171 manages the time for causing the image forming apparatus 100 to transition to sleep according to the sleep transition time designated through the operation unit 172. The sleep transition time may be selected from a plurality of set values such as 10 seconds, 1 minute, 5 minutes, 10 minutes,. The CPU 171 starts measuring a timer when the image formation is completed, and causes the image forming apparatus 100 to transition to sleep when the timer value reaches the sleep transition time. For example, when the sleep transition time is set to 10 seconds, the image forming apparatus 100 transitions to sleep when 10 seconds have elapsed since the image formation was completed. The CPU 171 executes the second welding detection during this 10 seconds. As described above, the CPU 171 may execute the first welding detection when returning from sleep.

<Second welding detection>
The second welding detection executed when the image forming job is completed will be described with reference to FIG. In FIG. 5, S701 and S702 are optional and will be described later. In S501, the CPU 171 switches the first relay 501 off while keeping the second relay 502 on. That is, the CPU 171 switches the control signal 503 to the low level and maintains the control signal 504 at the high level. In S502, the CPU 171 waits for a predetermined time. The predetermined time is a time required to transit to a state where the relay is stably turned off (a state where chattering is settled), and is a so-called relay make time (eg, 100 ms). When the CPU 171 confirms that a predetermined time has elapsed with a timer, a counter, or the like, the process proceeds to S503.

  In S503, the CPU 171 determines whether or not the first relay 501 is welded based on the detection signal 506 output from the zero cross detection circuit 505. For example, the CPU 171 determines whether the zero cross is detected by the zero cross detection circuit 505 based on the detection signal 506 output from the zero cross detection circuit 505. Since the first relay 501 is turned off, zero crossing is not originally detected. However, when the first relay 501 is welded, a zero cross is detected. Therefore, when the CPU 171 detects the zero cross, it determines that the first relay 501 is welded and proceeds to S504. If the zero cross cannot be detected, the CPU 171 determines that the first relay 501 is not welded and proceeds to S505.

  In S504, the CPU 171 stores a welding detection result indicating that the first relay 501 is welded in the RAM 175. Even when the first relay 501 is not welded, the CPU 171 may store a welding detection result indicating that the first relay 501 is not welded in the RAM 175. Thereafter, the process proceeds to S505. In S505, the CPU 171 switches the second relay 502 off by switching the level of the control signal 504 from the high level to the low level. As a result, the heater 601 transitions to the power saving mode.

<First welding detection>
The first welding detection will be described with reference to FIG. In step S601, the CPU 171 switches on the second relay 502 while keeping the first relay 501 off in order to execute welding detection. In S602, the CPU 171 waits for a predetermined time. The predetermined time is a time required to make a transition to a state in which the relay is stably turned off. In step S <b> 603, the CPU 171 determines whether the first relay 501 is welded based on the detection signal 506 output from the zero cross detection circuit 505. If the first relay 501 is not welded, the process proceeds to S604, and the CPU 171 switches the first relay 501 on. On the other hand, if the first relay 501 is welded, the CPU 171 proceeds to S605. In S605, the CPU 171 notifies the welding of the relay. For example, the CPU 171 outputs a message indicating that the relay is welded, a message indicating that repair is necessary, and the like to the display device of the operation unit 172. In S606, the CPU 171 switches the second relay 502 off.

  As described above, in this embodiment, if the welding is not detected by the second welding detection executed at the end of the image formation, the first welding detection is skipped. Therefore, according to the present embodiment, an image forming apparatus that performs welding detection of a relay that can reduce the waiting time is provided.

  In the above description, the first welding detection and the second welding detection are described as being executed for each image forming job, but may not be executed each time the image forming job is executed. For example, the first welding detection may be performed when the image forming apparatus 100 is activated, and the second welding detection may be performed when the image forming apparatus 100 is shut down. Alternatively, the second welding detection may be performed when the image forming apparatus 100 transitions to sleep, and the first welding detection may be performed when the image forming apparatus 100 returns from sleep. However, in any case, if no welding is detected in the second welding detection, the first welding detection is skipped. By skipping the first welding detection in this way, the number of times the relay contact is opened and closed decreases, so the life of the relay will be extended.

<Welding detection in consideration of 24VIL power supply>
The CPU 171 may determine whether or not welding detection can be performed by detecting a relay operating voltage supplied from the 24VIL power supply when image formation is completed. As described above, when the maintenance door 145 is opened, the 24VIL power supply is turned off, the first relay 501 and the second relay 502 are both turned off, and the supply of power to the heater 601 is stopped. In this case, regardless of the levels of the control signals 503 and 504, the first relay 501 and the second relay 502 are turned off, and the CPU 171 cannot perform welding detection. In particular, in the above-described embodiment, the CPU 171 determines that no welding has occurred based on the fact that zero crossing could not be detected. Therefore, even when the supply of power from the 24VIL power supply is stopped, the second relay 502 is turned off and zero crossing is not detected. That is, even if the first relay 501 is welded, zero crossing is not detected, so the CPU 171 erroneously determines that it is not welded. Therefore, the CPU 171 may determine whether or not the welding detection can be correctly performed by detecting whether or not power is supplied from the 24VIL power source.

  As shown in FIG. 5, S701 and S702 are added. In step S701, the CPU 171 determines whether the first relay 501 and the second relay 502 are operable based on the 24VIL detection signal 707. For example, if the 24VIL detection signal 707 is at a high level, the CPU 171 determines that the 24VIL power supply is supplying power. If the 24VIL detection signal 707 is at a low level, the CPU 171 determines that the 24VIL power supply is not supplying power. If the first relay 501 and the second relay 502 are operable, the CPU 171 proceeds to S503 and executes welding detection. On the other hand, if the first relay 501 and the second relay 502 are not operable, the CPU 171 proceeds to S702. In S702, the CPU 171 stores in the RAM 175 information indicating that the second welding detection could not be executed (the relay was inoperable).

  When considering the 24VIL power supply, the CPU 171 indicates whether or not information indicating that the second welding detection could not be executed is stored in the RAM 175 in S401 illustrated in FIG. That is, the CPU 171 determines whether or not the second welding detection is correctly executed. If the second welding detection is correctly executed, the CPU 171 further determines whether or not the first relay 501 is detected by the second welding detection. If it is detected that the first relay 501 is welded, the CPU 171 proceeds to S402. If it is not detected that the first relay 501 is welded, the CPU 171 proceeds to S403. On the other hand, if the second welding detection is not correctly executed, the CPU 171 executes the first welding detection without depending on the result of the second welding detection. That is, the CPU 171 proceeds from S401 to S402.

  Thus, at the execution timing of the second welding detection, the CPU 171 may determine whether or not the image forming apparatus 100 is in a state in which the second welding detection can be correctly executed. Thereby, it will be possible to avoid the situation where the first welding detection is erroneously skipped. Thereby, it becomes possible to more correctly determine whether or not the first relay 501 is welded. In addition, it may be possible to avoid a situation in which image formation is performed even though the first relay 501 is welded.

  In the above-described embodiment, the welding detection of the first relay 501 has been described as being performed. However, the welding detection may be performed on the second relay 502. In this case, in the above description, the first relay 501 may be read as the second relay 502, and the second relay 502 may be read as the first relay 501.

  Further, the first welding detection for the second relay 502 may be executed continuously after the first welding detection of the first relay 501 is completed. In this case, when the second welding detection of the first relay 501 is completed, the second welding detection for the second relay 502 is executed. In order to reduce the welding detection time, when the first welding detection and the second welding detection of the first relay 501 are completed, the first welding detection and the second welding detection of the second relay 502 are performed at the next execution timing. May be executed. In this manner, welding detection may be executed alternately for the first relay 501 and the second relay 502. Thus, since only one of the first relay 501 and the second relay 502 is a detection target in one welding detection, it will be possible to reduce the time required for one welding detection to about half. .

<Summary>
An example of a function realized by the CPU 171 executing the control program will be described with reference to FIG. All or some of these functions may be realized by a logic circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Logic Array). As described with reference to FIG. 3, one of the neutral line N and the hot line H that supply the power supplied from the AC power supply 550 to the load functions as the first line. Further, the other of the neutral line N and the hot line H functions as a second line. In the above embodiment, the hot line H is the first line and the neutral line N is the second line. However, these relations may be reversed. The first relay 501 is an example of a relay that turns on / off the first line. The second relay 502 is an example of a relay that turns on / off the second line.

  The supply state monitoring unit 801 monitors the supply state of power at a position subsequent to the first relay 501 in the first line. For example, the supply state monitoring unit 801 outputs a signal indicating that power is supplied to the welding detection unit 802 if the zero cross detection circuit 505 detects the zero cross. The supply state monitoring unit 801 outputs a signal indicating that power is not supplied to the welding detection unit 802 unless a zero cross is detected. In other words, the supply state monitoring unit 801 does not output a signal indicating that power is supplied to the welding detection unit 802 unless a zero cross is detected. As described in S403, the relay control unit 805 controls the first relay 501 and the second relay 502 to be turned on when the image forming job is started. As described with respect to S501 and S601, the relay control unit 805 turns on the second relay 502 and turns off the first relay 501 when the welding detection for detecting whether or not the first relay 501 is welded is started. Control.

  The first condition determination unit 803 determines whether or not a first execution condition for executing the first welding detection is satisfied. The second condition determination unit 804 determines whether a second execution condition for executing the second welding detection is satisfied. The first execution condition is, for example, that the result of the second welding detection stored in the storage unit 810 indicates that the first relay 501 is welded. The welding detection unit 802 performs the first welding detection if the result of the second welding detection indicates that the first relay 501 is welded. In particular, if the result of the second welding detection does not indicate that the first relay 501 is welded, the welding detection unit 802 skips the first welding detection. As a result, the image forming apparatus 100 that can shorten the waiting time associated with detection of welding of the relay as compared with the related art is realized.

  The first execution condition may be that the image forming apparatus 100 is instructed to execute an image forming job and the result of the second welding detection indicates that the first relay 501 is welded. In this case, the second execution condition is that the image forming apparatus 100 ends the image forming job. In the image forming job, since the heater 601 is heated, it is necessary to protect the heater 601 from overheating by switching the first relay 501 off. Therefore, when the start of the image forming job is instructed from the operation unit 172, it will be necessary to detect whether or not the first relay 501 is welded.

  Further, the first execution condition may be that the result of the second welding detection indicates that the image forming apparatus 100 is activated and the first relay 501 is welded. In this case, the second execution condition is that the image forming apparatus 100 is instructed to stop through the operation unit 172. The image forming apparatus 100 is often activated when an operator desires image formation. Accordingly, when the image forming apparatus 100 is activated, there is a high possibility that image formation will be started, and it will be necessary to detect whether or not the first relay 501 is welded before image formation.

  The first execution condition may be that the result of the second welding detection indicates that the image forming apparatus 100 returns from the power saving mode (sleep) and the first relay 501 is welded. . In this case, the second execution condition is that the image forming apparatus 100 satisfies the transition condition to the power saving mode. When the second welding detection is completed, the CPU 171 shifts the image forming apparatus 100 to the power saving mode. When the operator operates the operation unit 172 to return the image forming apparatus 100 from the sleep mode, the operator may wish to form an image. Therefore, when the image forming apparatus 100 returns from sleep, welding detection should be executed.

  As described above, the welding detection unit 802 executes the second welding detection when the image forming apparatus 100 stops, when the image forming job ends, or when the image forming apparatus 100 shifts to the power saving mode. In addition, the welding detection unit 802 performs the first welding detection when the image forming apparatus 100 is activated, when the image forming apparatus 100 starts an image forming job, or when the image forming apparatus 100 returns from the power saving mode. Execute. However, when the result of the second welding detection does not indicate that the first relay 501 is welded, the first welding detection is skipped.

  The storage unit 810 of the RAM 175 functions as a storage unit that stores the result of the second welding detection. The welding detection unit 802 or the first condition determination unit 803 may determine whether or not the first relay 501 is welded based on the result of the second welding detection stored in the storage unit 810. When the first relay 501 is welded, first welding detection is performed. When the first relay 501 is not welded, the first welding detection is skipped. As a result, the image forming apparatus 100 that can shorten the waiting time associated with detection of welding of the relay as compared with the related art is realized. Note that the storage unit 810 may be a rewritable nonvolatile storage device such as an EEPROM. In this case, a battery for holding information in the RAM 175 may be unnecessary.

  As described with respect to S604, when it is determined that the first relay 501 is not welded by the first welding detection, the relay control unit 805 switches the first relay 501 from OFF to ON to execute the image forming job. As a result, the heater 601 starts to heat up. That is, when the soundness of the first relay 501 is confirmed, the heater 601 is immediately turned on, so that the waiting time for the operator will be reduced.

  As described in regard to S605, the display device of the operation unit 172 may function as an output unit that outputs the result of the first welding detection. In particular, when the first welding detection reveals that the first relay 501 is welded, the output means outputs a message notifying that the first relay 501 is welded. As a result, the operator will understand that the first relay 501 has failed and will be able to request the manufacturer to replace the first relay 501. The output unit may be a communication device that transmits the message to an administrator, a manufacturer, or the like.

  As described with reference to FIG. 1, a maintenance door 145 that is opened when the image forming apparatus 100 is maintained may be provided. When the maintenance door 145 is closed, the door switch 760 connects a 24 VIL power source, which is a relay power source, to each of the first relay 501 and the second relay 502. Further, the door switch 760 does not connect the 24VIL power source to each of the first relay 501 and the second relay 502 when the maintenance door 145 is opened. Thereby, when the maintenance door 145 is opened, an AC voltage is not applied to the heater 601.

  As described regarding S701 and S702, if the maintenance door 145 is opened at the timing of executing the second welding detection, the first relay 501 and the second relay 502 become inoperable. That is, the welding detection unit 802 cannot execute the second welding detection. Therefore, in such a case, when the next execution timing of the first welding detection arrives, the first welding detection should be executed regardless of the result of the second welding detection. Therefore, the holding unit 811 of the RAM 175 functions as a holding unit that holds information indicating whether or not the second welding detection is performed. If the relay power supply is not connected to each of the first relay 501 and the second relay 502 when starting the second welding detection, the welding detection unit 802 does not perform the second welding detection, and Information indicating that the second welding detection has not been executed is held in the holding unit 811. In addition, if the relay power supply is connected to each of the first relay 501 and the second relay 502 when starting the second welding detection, the welding detection unit 802 executes the second welding detection. Furthermore, if information indicating that the second welding detection has not been performed is not held in the holding unit 811, the welding detection unit 802 performs the first detection according to the result of the second welding detection stored in the storage unit 810. Do not perform one welding detection. If the information indicating that the second welding detection has not been executed is held in the holding unit 811, the welding detection unit 802 does not depend on the result of the welding detection stored in the storage unit 810, and the first detection is not performed. Perform welding detection. Thereby, it will be possible to avoid that the second welding detection and the first welding detection are not continuously executed.

  The supply state monitoring unit 801 may detect a zero cross of an AC voltage applied to the load via the first line as a power supply state. The welding detection unit 802 determines that the first relay 501 is welded when the zero state is detected by the supply state monitoring unit 801 in the welding test, and the first relay 501 if the zero state is not detected by the supply state monitoring unit 801. It may be determined that is not welded.

  The semiconductor switch 510 functions as a power switch for turning on / off the second line in order to control the power supplied to the heater 601 of the fixing device as a load. The temperature sensor 602 functions as a temperature detection unit that detects the temperature of the heater 601. The temperature control unit 806 functions as a temperature control unit that controls the semiconductor switch 510 so that the temperature detected by the temperature sensor 602 becomes the target temperature. Note that the temperature control unit 806 may control the wave number of the AC voltage supplied to the heater 601 with reference to the zero cross of the AC voltage energized through the first line detected by the supply state monitoring unit 801. That is, the zero-crossing detection circuit 505 for wave number control can be used for the welding test or shared, so that the number of parts can be reduced.

  When the switching unit 807 determines that the first relay 501 is not welded in both the first welding detection and the second welding detection, the switching unit 807 sets each target of the first welding detection and the second welding detection from the first relay 501 to the first welding 501. It may function as switching means for switching to the two relays 502. Accordingly, the first relay 501 and the second relay 502 can be detected alternately. In addition, since only one relay is a detection target in one welding detection, it will be possible to reduce the time for one welding detection.

  Note that the CPU 171 may be configured to execute welding detection at a timing when image formation is completed, and not to perform welding detection at all at a timing when image formation is started. However, in this case, in an image forming apparatus that sleeps as soon as image formation is completed, the CPU 171 cannot output the result of welding detection to the operation unit 172. Further, when transitioning to sleep, the result of welding detection may be erased from the RAM 175. In the first place, when transitioning to sleep, the 24VIL power supply is turned off, and the CPU 171 may not be able to perform welding detection. In this case, the CPU 171 will not be able to output the result of the welding detection to the operation unit 172 when returning from sleep. This embodiment will be advantageous because the first welding detection is executed in accordance with the execution result of the second welding detection.

  171 ... CPU, 175 ... RAM, N ... neutral line, H ... hot line, 501 ... first relay, 502 ... second relay, 505 ... zero cross detection circuit, 550 ... AC power supply, 601 ... heater, 602 ... temperature sensor,

Claims (11)

An image forming apparatus,
A first line that is one of a neutral line and a hot line that supplies power supplied from an AC power source to the load;
A second line which is the other of the neutral line and the hot line;
A first relay for turning on / off the first line;
A second relay for turning on / off the second line;
Monitoring means for monitoring a power supply state at a position subsequent to the first relay in the first line;
Relay control means for controlling on / off of each of the first relay and the second relay;
When the first execution condition is satisfied, first welding detection is performed to detect whether or not the first relay is welded according to the power supply state monitored by the monitoring unit, and the second execution condition is satisfied. And welding detection means for performing second welding detection for detecting whether or not the first relay is welded according to the power supply state monitored by the monitoring means;
Storage means for storing the result of the second welding detection,
The first execution condition is that the image forming apparatus is instructed to execute an image forming job, and the result of the second welding detection stored in the storage means is that the first relay is welded. Is that
The second execution condition is that the image forming apparatus ends the image forming job,
The welding detection means performs the first welding detection if the result of the second welding detection indicates that the first relay is welded, and indicates that the first relay is welded. If the second welding detection result does not indicate, skip the first welding detection,
The relay control unit controls the second relay to be on and the first relay to be off while the welding detection unit is executing the first welding detection or the second welding detection. And
Further, the relay control means controls the first relay and the second relay to be turned on when an image forming job is started, respectively. An image forming apparatus,
A first line that is one of a neutral line and a hot line that supplies power supplied from an AC power source to the load;
A second line which is the other of the neutral line and the hot line;
A first relay for turning on / off the first line;
A second relay for turning on / off the second line;
Monitoring means for monitoring a power supply state at a position subsequent to the first relay in the first line;
Relay control means for controlling on / off of each of the first relay and the second relay;
When the first execution condition is satisfied, first welding detection is performed to detect whether or not the first relay is welded according to the power supply state monitored by the monitoring unit, and the second execution condition is satisfied. And welding detection means for performing second welding detection for detecting whether or not the first relay is welded according to the power supply state monitored by the monitoring means;
Storage means for storing the result of the second welding detection,
The first execution condition is that the image forming apparatus is activated and the result of the second welding detection stored in the storage means indicates that the first relay is welded. Yes,
Said second execution condition state, and are said image forming apparatus is instructed to stop,
The welding detection means performs the first welding detection if the result of the second welding detection indicates that the first relay is welded, and indicates that the first relay is welded. If the second welding detection result does not indicate, skip the first welding detection,
The relay control unit controls the second relay to be on and the first relay to be off while the welding detection unit is executing the first welding detection or the second welding detection. And
Furthermore, the relay control unit, images forming device you and controls to turn on each said first relay and said second relay when the image forming job is started. An image forming apparatus,
A first line that is one of a neutral line and a hot line that supplies power supplied from an AC power source to the load;
A second line which is the other of the neutral line and the hot line;
A first relay for turning on / off the first line;
A second relay for turning on / off the second line;
Monitoring means for monitoring a power supply state at a position subsequent to the first relay in the first line;
Relay control means for controlling on / off of each of the first relay and the second relay;
When the first execution condition is satisfied, first welding detection is performed to detect whether or not the first relay is welded according to the power supply state monitored by the monitoring unit, and the second execution condition is satisfied. And welding detection means for performing second welding detection for detecting whether or not the first relay is welded according to the power supply state monitored by the monitoring means;
Storage means for storing the result of the second welding detection,
The first execution condition is that the image forming apparatus returns from the power saving mode, and the result of the second welding detection stored in the storage unit is that the first relay is welded. Is that
It said second execution condition state, and are said image forming apparatus transition condition to the power saving mode is satisfied,
The welding detection means performs the first welding detection if the result of the second welding detection indicates that the first relay is welded, and indicates that the first relay is welded. If the second welding detection result does not indicate, skip the first welding detection,
The relay control unit controls the second relay to be on and the first relay to be off while the welding detection unit is executing the first welding detection or the second welding detection. And
Furthermore, the relay control unit, images forming device shall be the characterized in that said first relay and said second relay to be controlled on the respective when the image forming job is started. Said monitoring means, the image of any one of claims 1 to 3, characterized in that to detect the zero crossing of the AC voltage applied to the load via the first line as a supply state of the power Forming equipment. The relay control unit switches the first relay from off to on to execute the image forming job when it is determined by the first welding detection that the first relay is not welded. Item 5. The image forming apparatus according to any one of Items 1 to 4 . The image forming apparatus according to any one of claims 1 to 5, characterized by further comprising output means for outputting the results of the first weld detection. And the output means, when the first relay by the first welding detection is found to be welded, according to claim 6, characterized in that for outputting a message indicating that the first relay is welded The image forming apparatus described in 1. A maintenance door that is opened when the image forming apparatus is maintained;
When the maintenance door is closed, a relay power supply is connected to each of the first relay and the second relay, and when the maintenance door is opened, a relay power supply is not connected to each of the first relay and the second relay. A door switch,
Holding means for holding information indicating whether the second welding detection has been performed,
The welding detection means does not execute the second welding detection unless the relay power supply is connected to each of the first relay and the second relay when starting the second welding detection, and Information indicating that the second welding detection has not been performed is held in the holding means, and the relay power supply is connected to each of the first relay and the second relay when the second welding detection is started. If so, execute the second welding detection,
Further, the welding detection means responds to the result of the second welding detection stored in the storage means unless information indicating that the second welding detection has not been executed is held in the holding means. If the information indicating that the second welding detection has not been executed is held in the holding means, the second welding stored in the storage means is not executed or executed. without depending on the result of the detection, the image forming apparatus according to any one of claims 1 to 7, characterized in that to perform the first welding detection. The monitoring means detects a zero crossing of an AC voltage applied to the load via the first line as the power supply state,
The welding detection means determines that the first relay is welded when the zero cross is detected by the monitoring means, and the first relay is not welded unless the zero cross is detected by the monitoring means. The image forming apparatus according to any one of claims 1 to 8 , wherein the image forming apparatus is determined. A power switch for turning on / off the second line to control power supplied to a heater of the fixing device as the load;
Temperature detecting means for detecting the temperature of the heater;
Temperature control means for controlling the power switch so that the temperature detected by the temperature detection means becomes a target temperature, and
Said temperature control means, claims 1 and controls the number of waves of AC voltage supplied to the heater the zero crossing of the alternating voltage energizing the sensed said first line by said monitoring means as a reference the image forming apparatus according to any one of 9. If it is determined that the first relay is not welded in both the first welding detection and the second welding detection, the objects of the first welding detection and the second welding detection are determined from the first relay. the image forming apparatus according to any one of claims 1 to 10, characterized by further comprising a switching means for switching the two relays.

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